IEC qualification test applied to capacitively graded 13.8 kV bar samples energized with repetitive fast pulses

The paper investigates the repetitive fast pulse tests using IEC-TS 60034–18–42 as applied to 13.8 kV bar samples with two different stress grading systems: nonlinear resistive and capacitive. Insulated copper bars were furnished with a capacitive stress grading system consisting of aluminum foils embedded into the groundwall insulation forming a capacitively graded system. The effectiveness of the capacitive stress grading is shown by passing all of the IEC/TS 60034–18–42 qualification tests showing considerably lower temperature rise than resistive stress grading systems.